Corrosion prevention of iron and steel



252. COMPOSITIONS,

Patented June 24, 1930 PATENT OFFICE MARION M. HARRISON, OF AKRON, OHIO CORROSION PREVENTION OF IRON AND STEEL No Drawing.

My invention relates to the protection of iron and steel from the corrosive action of acids. It is particularly applicable to the pickling operation in iron or steel mills, wherein it is necessary to remove scale from iron sheets, rods, wire or billets. It is also useful for cleansing tubes from scale by pickling and for removing the scale and corrosion products that accumulate in water pipes. It may be used in any case Where iron or steel is to be freed from rust or oxides, or wherever it is necessary to treat iron or steel with acids and solution of the metal is undesirable. It is useful in any case in which it is necessary or desirable to use acidic materials in contact with iron or steel.

According to my invention as applied to pickling, the pickling solution has as an added ingredient, a small quantity of a derivative of 1 -2 diamino ethane. The amount of the organic material added may vary greatly but quantities ranging from .O2% to 25% have been found to produce good results. Of course, a lesser portion may be used if the inhibiting action need not be so great and correspondingly, the quantity may be increased greatly above the .25% if it should seem desirable.

In general, the compounds of this invention are easily handled in mill practice. Their activity is not destroyed by high temperatures, even up to 85 C. There are a number of such amino derivatives of ethane which function in this manner and they may be represented by the following general chemical constitution In the above representation of the constitutional formula, the chemical radicals at- Application filed. July 14,

1928. Serial No. 292,918.

tached to the nitrogen atoms are denoted by the symbols, R(a), R(b), R(e), and R(f); the radicals attached to the carbon atoms are represented by R(c), RM), R(g) and R(h).

R(a), R(b) and R(e) and R(f) may be of any of the following chemical groups or their equivalents:

H, CH CH CH CH CH CH (CI-I CH, CH CH CH CH (CH CH-CH CHQCHQCHQCHQC Q, (GH3)2CH-CH2CH2, CG S, s 4- 3: CB AC QL CG SC Z, C ILNH C H CH N H C H OH, C H

R(a), R(b), R(e) and R(f)'may also be any of the following chemical groups or their equivalents: NO, C H CH N0 C H,NO C H cl, but in the case of these more negative groups, not more than two should be used in each molecule.

R(c), R(d), R(g) and R(h) may be any of the following chemical radicals or their equivalents CH, CH CH CH CH (CH CH.CH

0.11.0113, 06H. (0H3 2, cart, 06H,

In this specification all the materials referred to are nitrogen derivatives of ethane. In general they may be prepared by heating the dihalogen derivative of ethane (or substituted ethanes) with the appropriate amino compound, although other methods of preparation may be employed.

By the term derivative, as used in this specification and claims, it is not intended to include molecular constitutions containing several strongly negative groups, as pointed out above, nor do I intend to include molecular constitutions containing still more highly negative groups, such as C ILCO, CH3 NO2 3, 3, etc.

The nomenclature used to denote the position of the substituted chemical groups is the conventional system. The structure of Exam the ethane molecule being considered to be as follows:

As examples of compounds of this class which have been found to have inhibitive properties, I may mention the following:

(para tolyl amino) ethane phenylamino) ethane (ortho tolyl amino) ethane ylyl ammo) ethane lpha naphthyl amino) ethane eta naphthyl amino) ethane henyl amino) 2-(ortho tolyl 31111110) ethane thyl ortho tolyl amino) ethane enzyl phenyl amino) ethane henyl nitros amino) ethane ethyl phenyl amino) ethane benzyl ammo) ethane yl amino)-2-methyl ethane ortho tolyl amjno)-2-methy1 ethane para tolyl am1n0)-2-methyl ethane (xylyl amino)-2-methyl ethane (alpha naphthyl amino)-2-methyl ethane (beta naphthyl amino)-2-methyl ethane (ethyl p enyl amino)-2-methy1 ethane (phenyl ortho tolyl diamino)-2-methyl ethane (phenyl nitros ammo)-2-methyl ethane henyl alpha naphthyl diamino)-2-methyl ethane henyl amino)-2-isopropyl ethane henyl amino)-2-pseudo butyl ethane thyl ortho tolyl amino)-2-methyl ethane henyl amino)-2-ethyl ethane henyl amino)-1-2-dimethyl ethane rtho tolyl amino)-1-2-dirnethy1 ethane ara tolyl amino)-1-2-climethyl ethane lpha naphthyl amino)-1-2-dimethyl ethane rtho tolyl amino)-2-ethyl ethane henyl amino)-2-2-dimethyl ethane henyl amino)-1-methvl-2-ethyl ethane phenyl amino)-1-2-diphenyl ethane phenyl amino) -1-2-2-trimethyl ethane o)-1-2-2-trimethy1 ethane (alpha naphthyl amino)-1-2-2-trimethyl ethane (phenyl amino)-1-1-2-2-tetra-methyl ethane (ortho tolyl amiuo)-1-1-2-2-tetra methyl ethane i (alpha naphthyl amino)-1-1-2-2-tetra methyl ethane The above examples which function in practicing this invention, serve to indicate the wide range of materials of this type which are of value as corrosion inhibitors. However, they are mentioned only as examples and this invention is not limited to these specific compounds. Many of these compounds do not contaminate the pickling solution with decomposition products, which produce a discolored surface on pickled sheets.

As illustrative of the manner in which the foregoing materials may be used and the effect which they have, the following examples are given:

A solution of sulphuric acid containing mmu'enrm'clouww man-unmannwxcmr'n'cwmwm mamas-ma.

HHHHHHHHHHHHHHHHHHHHHHHH a.

5.39% H 30 was kept at a temperature of 28 C. A highly polished steel cube was placed in the solution, causing an evolution of hydrogen at the rate of 5.72 cubic centimeters per minute per square decimeter of surface. When 0.25% of 1-2 di (phenyl amino) ethane (C H NH.CI-LCH NHC H is added, the same cube causes an evolution of only .051 cubic centimeters per minute per square decimeter of surface at the same temperature. When to the original solution, 1-2 di (ethyl ortho tolyl amino) ethane cH.c.H.N c.H. .oH.cH.

- annual-non.

is added to the extent of 0.1%, only .04 cubic centimeters of hydrogen per minute per square decimeter of surface is evolved.

In another case, a solution containing 5.39% of H SO. is heated to a temperature of 85 C.; at this temperature there is an evolution of hydrogen at the rate of 23 cubic centimeters per minute per square decimeter of surface when the polished cube is placed in the solution. The addition of 0.25% of the 1-2 di (phenyl amino) ethane causes a reduction of the corrosion to such a rate that only 5.7 cubic centimeters of hydrogen per minute per square decimeter of surface are evolved. When to the original solution there is added 0.1% of 12 di (ethyl ortho tolyl amino) ethane, the hydrogen evolution decreases to 4.6 cubic centimeters per minute per square decimeter surface.

As a further example of the protective action of these materials I may cite the following: A sheet of steel, about three inches square, weighing 47.42 grams, loses 0.29 grams after immersion for two hours in a 10% aqueous acetic acid solution at C. Under identical conditions, except that the solution contained 0.15% of 1-2 di (phenyl amino) ethane, a sheet of the same size, cut from the same large sheet of steel and weighing 49.59 grams, lost only .01 gram.

While only sulphuric and acetic acids are mentioned in the previous examples, these inhibitors are effective with muriatic, nitric, or any other acid solution.

It is apparent that all compounds of this class will not have inhibitive properties to the same degree, some of them being more active than the above cited, and some showing less activity.

It is apparent from the above series that by choosing a particular compound and varying the concentrations, almost any degree of inhibition may be reached. This is of value, since it is undesirable for most purposes to use an inhibitor which entirely eliminates the action of the acid on the metal.

What I claim is:

1. In the method of preventing corrosion of iron or steel by acid substances the step consisting in the addition of a derivative of 1-2 diamino ethane to the acid substances, as a corrosion inhibitor.

2. In the method of preventing corrosion of iron or steel by acid substances the step consisting in the addition to the acid substances of a derivative of 1-2 diamino ethane, wherein one of the hydrogen-atoms of each amino group is replaced by an organic radical, as a corrosion inhibitor.

3. In the method of preventing corrosion of iron or steel by acid substances the step consisting in the addition to the acid substances of a derivative of 1-2 diamino ethane, wherein one of the hydrogen atoms of each amino group is replaced by an aromatic group, as a corrosion inhibitor.

252. COMPOSITIONS,

4. In the method of preventing corrosion of iron or steel by acid substances the step consistin in the addition to the acid substances o a derivative of 1-2 diamino ethane, wherein both hydrogen atoms of each amino group are replaced by two organic groups, one of which is an aromatic radical, as a. corrosion inhibitor.

5. In the method of preventing corrosion of iron or steel by acid substances the step consisting in the addition to the acid substances of the organic base made by heating one mol of dihalogen ethane and more than two mols of aromatic amine, as a corrosion inhibitor.

6. In the method of preventing corrosion of iron or steel by acid substances the step consisting in adding to the acid substances a di-aryl substituted 1-2 diamino ethane as a. corrosion inhibitor.

7 In the method of preventing corrosion of iron or steel by acid substances the step consisting in adding to the acid substances a derivative of di-aryl substituted 1-2 diamino ethane, as a corrosion inhibitor.

8. In the method of preventing corrosion' of iron or steel by acid substances the step consisting in adding to the acid substances 1-2 di (phenyl amino) ethane, as a corrosion inhibitor.

9. An acid substance for treating iron or steel having incorporated therein a derivative of 1-2 diamino ethane for retarding corrosion.

10. An acid substance for the treatment of iron or steel havin incorporated therein 1-2 di (phenyl amino? ethane.

11. In the method of preventing corrosion of iron or steel by acid substances the step consisting in addin to the acid substances a derivative of 1-2 'amino ethane, wherein one of the hydrogen atoms of each amino group is replaced by a phenyl group, as a corrosion inhibitor.

12. In the method of preventing corrosion of iron or steel by acid substances the step consisting in adding to the acid substances a derivative of 1-2 diamino ethane, wherein two of the hydrogen atoms of each amino group are replaced by two phenyl groups, as a corrosion inhibitor.

In testimony whereof, I afiix my signature.

MARION M. HARRISON. 

